Darwiniana | Page 4

and the

strongest in the long-run alone survive.
The duty of reviewing this volume in the American Journal of Science
would naturally devolve upon the principal editor,' whose wide
observation and profound knowledge of various departments of natural
history, as well as of geology, particularly qualify him for the task. But
he has been obliged to lay aside his pen, and to seek in distant lands the
entire repose from scientific labor so essential to the restoration of his
health--a consummation devoutly to be wished, and confidently to be
expected. Interested as Mr. Dana would be in this volume, he could not
be expected to accept this doctrine.
Views so idealistic as those upon which his "Thoughts upon Species"
[I-2] are grounded, will not harmonize readily with a doctrine so
thoroughly naturalistic as that of Mr. Darwin. Though it is just possible
that one who regards the kinds of elementary matter, such as oxygen
and hydrogen, and the definite compounds of these elementary matters,
and their compounds again, in the mineral kingdom, as constituting
species, in the same sense, fundamentally, as that of animal and
vegetable species, might admit an evolution of one species from
another in the latter as well as the former case.
Between the doctrines of this volume and those of the other great
naturalist whose name adorns the title-page of this journal, the widest
divergence appears. It is interesting to contrast the two, and, indeed, is
necessary to our purpose; for this contrast brings out most prominently,
and sets in strongest light and shade, the main features of the theory of
the origination of species by means of Natural Selection.
The ordinary and generally-received view assumes the independent,
specific creation of each kind of plant and animal in a primitive stock,
which reproduces its like from generation to generation, and so
continues the species. Taking the idea of species from this perennial
succession of essentially similar individuals, the chain is logically
traceable back to a local origin in a single stock, a single pair, or a
single individual, from which all the individuals composing the species
have proceeded by natural generation. Although the similarity of
progeny to parent is fundamental in the conception of species, yet the
likeness is by no means absolute; all species vary more or less, and
some vary remarkably--partly from the influence of altered
circumstances, and partly (and more really) from unknown

constitutional causes which altered conditions favor rather than
originate. But these variations are supposed to be mere oscillations
from a normal state, and in Nature to be limited if not transitory; so that
the primordial differences between species and species at their
beginning have not been effaced, nor largely obscured, by blending
through variation. Consequently, whenever two reputed species are
found to blend in Nature through a series of intermediate forms,
community of origin is inferred, and all the forms, however diverse, are
held to belong to one species. Moreover, since bisexuality is the rule in
Nature (which is practically carried out, in the long-run, far more
generally than has been suspected), and the heritable qualities of two
distinct individuals are mingled in the offspring, it is supposed that the
general sterility of hybrid progeny interposes an effectual barrier
against the blending of the original species by crossing.
From this generally-accepted view the well-known theory of Agassiz
and the recent one of Darwin diverge in exactly opposite directions.
That of Agassiz differs fundamentally from the ordinary view only in
this, that it discards the idea of a common descent as the real bond of
union among the individuals of a species, and also the idea of a local
origin--supposing, instead, that each species originated simultaneously,
generally speaking, over the whole geographical area it now occupies
or has occupied, and in perhaps as many individuals as it numbered at
any subsequent period.
Mr. Darwin, on the other hand, holds the orthodox view of the descent
of all the individuals of a species not only from a local birthplace, but
from a single ancestor or pair; and that each species has extended and
established itself, through natural agencies, wherever it could; so that
the actual geographical distribution of any species is by no means a
primordial arrangement, but a natural result. He goes farther, and this
volume is a protracted argument intended to prove that the species we
recognize have not been independently created, as such, but have
descended, like varieties, from other species. Varieties, on this view,
are incipient or possible species: species are varieties of a larger growth
and a wider and earlier divergence from the parent stock; the difference
is one of degree, not of kind.
The ordinary view--rendering unto Caesar the things that are
Caesar's--looks to natural agencies for the actual distribution and

perpetuation of species, to a supernatural for their